In recent years, progress has been made in the research and development of organic electroluminescent elements, which are light-emitting elements that rely on the phenomenon of electroluminescence of organic material. In a structure proposed for a display device using these light-emitting elements, blue, green, and red light-emitting elements are arranged on a substrate.
It is important to improve light-extraction efficiency in the light-emitting elements, for example from the standpoint of reducing power consumption. Conventionally, technology has therefore been proposed to improve light-extraction efficiency by adopting a resonator (cavity) structure in the light-emitting element (see, for example, Patent Literature 1). Patent Literature 1 discloses light-emitting elements in which a lower electrode (mirror), transparent conductive layer, hole transport layer, light-emitting layer, electron transport layer, and upper electrode (half mirror) are laminated, and discloses adjusting optical distance between the mirror and the half mirror in order to maximize the blue, green, and red light-extraction efficiency (paragraph 0012).
Furthermore, in addition to improving light-extraction efficiency in the display device, it is also important to achieve excellent color reproducibility. In order to improve color reproducibility, it is necessary to improve the color purity of the light-emitting elements of each color. Technology has been proposed for improving such color purity of emitted light by providing a color filter above the light-emitting elements, thereby excluding unwanted wavelength components.